Electric burglar-alarm.



No. 742,073. PATENTED OCT. 20, 1903. B. F. SGHUBERT.

1' NVENTOR UNITED STATES Patented October 20, 1903.

PATENT OFFICE.

BERNHARD F. SCHUBERT, OF WASHINGTON, DISTRICT OF COLUMBIA,

ASSIGNOR OF ONE-HALF TO RUDOLPH SIMMS, OF WASHINGTON, DIS- TRICT OF COLUMBIA.

ELECTRIC BURGLAR-ALARM.

SPECIFICATION forming part of Letters Patent No. 742,073, dated October 20, 1903.

Application filed February 18, 1903. Serial No. 143,990. (No model.)

T0 on whom it may concern:

Be it known that LBERNHAED F. ScHUBERT, a citizen of the United States, residing at Washington, in the District of Columbia, have invented new and useful Improvements in Electric Burglar-Alarms, of which the following is a specification.

My invention relates to new and useful improvements in electrical burglar-alarms; and its objectis to provide a simple and inexpensive device which is adapted to be operated by the turning of a door-knob in either direction.

The alarm can be readily applied to the ordinary form of door.

The invention consists in the novel construction and combination of parts hereinafter more fully described and claimed, and illustrated in the accompanying drawing showing the preferred form of my invention, and in which- Figure l is a view showing my improved alarm attached to a door. Fig. 2 is a detail view of the attachment, and Fig. 3 isa similar view of a modified form of alarm attachment.

Referring to the figures by numerals of reference, 1 is a base-plate adapted to be secured to a door in any suitable manner and having an aperture 2 therein for the reception of the spindle 3 of a door-knob. A collar t is secured upon said spindle and is provided with oppositely-curved arms 5. Binding-posts 6 are arranged at the lower corners of the plate 1 and each is connected to one of the wires 7 of a circuit. A spring 8 is fastened to the plate 1 at one end by one of the bindingposts and is arched around the collar 4; and forked at its free end, as shown at 9. A plate 10 is secured to the other binding-post and projects into the forked end of spring 8. The wires 7 are so arranged within the door as to prevent tampering therewith, and a switch 11 may be connected to one of them, so as to prevent the sounding of the alarm when desired. Any suitable means, such as spring-contacts 12, may be provided for completing the circuit between the wires 7 within the door and the wires 13, which are removed from said door and include the alarm 14. and battery 15. When the door is closed and electrical connection established between wires 7 and 1b, the door-knob cannot be turned in either direction without bringing one of the arms 5 into contact with spring 8. If swung to the left, the arms will swing the outer tine of fork 9 into contact with plate 10, and if the knob is turned in the other direction the inner tine of said fork will be brought into contact with the plate. In both instances an electrical circuit is established and the alarm 14 is sounded. It will of course be understood that the spring 8 and plate 10 are insulated from base 1, or, if desired, said base can be formed of non-conducting material.

In Fig. 3 I have shown a modified form of attachment. As illustrated in this figure, curved spring-arms 16 extend from opposite sides of the collar 4, and a coiled wire 17 extends from the collar to a binding-post 18, which is connected to one of the wires 7. A curved plate 19 is fastened upon base 1 and is concentric with collar l, and a bindingpost 20, to which the other wire 7 is secured, is arranged upon this plate 19. When the knob is turned in either direction, one of the spring-arms 16 is brought into contact with plate 19 and establishes a circuit through the wires 7.

It will be seen that the device is extremely simple and inexpensive, and the collar at can be readily attached to the spindle of an ordinary door-lock.

In the foregoing description I have shown the preferred form of my invention; but Ido not limit myself thereto, as I am aware that modifications may be made therein without departing from the spirit or sacrificing any of the advantages thereof, and I therefore reserve the right to make such changes as fairly fall within the scope of my invention.

Having thus described the invention, what is claimed as new is 1. In an alarm attachment of the character described, the combination with a base-plate having the wires of an electric circuit connected thereto; of a contact-plate connected to one of the wires, a spring connected to the other wire, a forked end thereto straddling the contact-plate, a revolulole collar, and an and straddling the contact-plate, a revoluble IO arm thereto adapted to contact With the collar, and oppositely-extending arms to the spring. collar adapted to operate said spring.

2. In an alarm attachment of the character In testimony whereof I aflix my signature described, the combination with a base-plate in presence of two Witnesses.

having Wires of an electrical circuit oonnect- BERNHARD F. SOHUBERT. ed thereto; of a contact-plate connected to Witnesses: one of the Wires, a curved spring connected EMMA G. FRASER,

to the other wire, a forked end to said spring SARAH J. MOORE. 

